Refining oil



UhlllT-Eifij STATES PHILIP 'r. SHARPLES. or

MERION. PENNSYLVANIA.

REFINING OIL.

N0 Drawing. Continuation of application Serial No. 495.083, filed August 24,1921. filed April 6, 1922.

specification.

This invention 15 a method which effects the refining of mineral oil so as to produce large yields of superior products. with avoidance of the destructive actions that result in the methods heretofore practiced, particularly in the separation of wax from lubricating distillates and this application is acontinuation of my application. filed August 24, 1921, Serial Number 495,083, as to all matter common to the two applications.

A specific desideratum effected is the removal of wax from certain lubricating distillates without the cracking distillation which has been practiced heretofore to effect the so called crystallization" of such wax as an essential step in its removal and which cracking has resulted in the reduction of the viscosity, the value and the yield of llbbl'i', eating oil.

It is to be understood that the wax in such lubricating distillates is in an intermediate condition between the so called amorphous wax and the so called crystalline wax. \Vax in the intermediate form clogs a'filter so that it cannot satisfactorily be pressed,

does not respond in any satisfactory manner to the cold settling treatment, and it has not been practicable to separate it' by centrifugal force successfully by known methods, so that heretofore it has been considered to be commercially impracticable, if not altogether impossible, to remove this wax from the oil without subjecting the'oil and the wax to a treatment which changes the physical characteristicsof the wax, but which incidentally changes the physical characteristics of the oil so as greatly to reduce thevalue-t-hereof.

In accordance with my invention in the preferred practice thereof, the lubricating constituents of the oil are distilled off so as to avoid substantial cracking or substantial injury to the oil and as much of the oil as practicable is taken in a cut which will contain primarily the .so-called crystalline Wax, which wax can be removed by filter Specification of Letters Patent.

Patented May 23, 1922.,

This application Serial No. 550,206.

pressing. The cut which follows contains wax in what I term the intermediate" state, but it is to be understood that my invention relates to the treatment of oil containing such wax irrespective of the manner in which the fraction of oil is obtained. An example of a type of material which contains wax in the intermediate state is the "3% stock so-called by reason of the gravity at which a cut is taken which corresponds approximately to 3l B.

This lubricating distillate or stock, containing wax in the intermediate" form, is

now specially treated for the removal ofwax by dilution with naphtha so as to reduce the density of the oil relatively to the wax, chilling the product so as to precipitate the wax while maintaining the fluidity of th oil and centrifuging in a special manner, so as to continuously separate and separately discharge the wax and the wax free oil, preferably by the use of a carrier liquid for floating olf thenvax.

The treatment is applied to the stock directly or to a residue obtained by distilling off say 35% o a cut such as the "34 stock", without substantial cracking, as distinguished from the distillation of the bulk tliereof with its accompanying. deterioration ofthe oil found unavoidable in the rior practice of removing the wax, particu arly from the more viscous and valuable fractions. r

I effect the dilution by using enough naphtha to prevent the oil from becoming solid or semi-solid upon chilling by the use of a diluent of such light character and large excess as to increase the difference in gravity between the oil and wax so that they can be separated and separately dischargedcontinuouslyin a centrifual operation after precipitation of the wax by appropriate chilling. The wax in the intermediate form, in which it is found in the lubricating distillate that has not been subjected to the objectionable destructive distillation, will absorb a certain amount of naphtha with conseql ent reduction of its specific gravity as well as that of the oil, so that in the treatment for centrifua l separation there should be not merely dilution but dilution beyond the saturation of the wax or dilution that results in such difierence'in specific gravity 7 The chilling of the than is. necessary, for the desired'regular chilling is not effected through wax which deposits on the .cooling surfaces and violent agitation of theaoil tends to disseminate the 2o agitation of theoil. To obtain good results it generall is necessary to chill to a tem-.

wax therethrou'gh and cause the wholeimixt-ure to,'set --{as a jelly. Consequentlythe chilling surfaces should be scraped regularly but slowly and without substantial perature 0 0 F. and I prefer to chill to a temperature of about 10 F.

The oil having'been chilled and the wax precipitated, the separation is" effected centrifu'gally, preferably in a centrifuge containmg a carrier li uid, which is desirably water that is held in the bowl against the wall thereof so that the separated wax will float off thereon, though a different carrier liquid such as brine may be used and the carrier liquid may flow through the bowl in accordance with known operations, as described in my U. S; Patent No. 1232104.

I have found that water is satisfactory as a carrier liquid and will not freeze even when centrifuging oil chilled to below zero, the air friction on the bowl shell keeping the temperature of the water above its freezing point. Water has the advantages of low cost, convenient supply and has much less I tendency to corrode the centrifugal than brine or most other aqueous carrier liquids.

In addition its specific gravity is more nearly that of the wax than brine or other practicable aqueous solutions and the adjustments required of the centrifuge are therefore less delicate.

In the indicated specific application of my method to the treatment of 34 stock 3 by distilling oil" 35%, I use fire and steam to effect the distillation so as to avoid substantia1 cracking, treat the residue remaining inlthe still with 70% of B.-naphtha havlng a close range of boiling points, heat to dissolve the wax, chill in contact with f chill ing surfaces which are scraped about .'-.once 1n ten minutes Without agitating the oil,- which is thus cooled to 10 F., and pass the mixture through the rotor of a suitably designed centrifuge (such for' instance as shown in my U. S. Patents Nos. 1232104 and lfiO1196) and containing water as a carrier liquid, the wax separated from the oil being floated off on the carrier liquid and the wax free oil being separately discharged, continuously.

A typical operation of my process as applied to an 011 having a paraffin base, 1s shown by the following diagram:

Wax cake Distillate Chillingand (3%). light lubrifilter press Heavy lubricating eating oil ing. Pressed oil distillate or "34 (35%). 2%). stock-steam dis- A tillation. Wax c Residue Diluting (13%).

65% chilling and continuous Heavy lubricatcentrifuging g oil (300 vis.)

naphtha re- (52%). moral.

III-this particular example four times as much heavy lubricating oil (300 second universal Saybolt viscosity at 100 has been produced by my method here disclosed as by the approved practice in'general use.

In handling crude oil having an asphaltic base, now commonly distilled with fire to coke, I prefer to distill according to the same procedure as is ordinarily used with a crude oil having a paraffin base, excepting that the 15% residue would be further distilled with cracking to secure a greater re covery of lubricating oil. I can thus obtain much more heavy lubricating oil from the same crude.

It is to be understood that in its broad aspects my invention is quite independent of the type of machine that is used or the details of operation and my claims of novelty are based upon my discovery that it is possible to treat a mixture of lubricating oil and wax intermediate the-so-called crystalline and amorphous .forms and separate the wax from the oil by, a continuous centrifugal operation. c

Having described my invention, I claim 1. The method of treating the residue obtained by distilling off lower boiling point constitutents from crude petroleum which consists in distilling the residue so that the oil shall not be cracked substantially, treating the distillate to effect the precipitation of the wax and maintain the fluidity of the oil so that they can be separated by centrifugal force, and centrifugally separating and separately discharging the wax and the wax freed oil continuously.

2. The method of treating the residue obtained by distilling off lower boiling point constituents from crude petroleum, which ooj consists indistilling the residue so that the oil shall not be cracked substantially, diluting the distillate with a solvent of lower -Specific gravity that will reduce the density of the oil relatively to that of the wax, chilling the diluted product so that the wax shall be precipitated and the oil maintained in fluid condition, and centrifugally separating and separatel discharging the wax and the wax freed oi continuously.

3. The method of treating the lubricating residue obtained b distilling ofi' the lower boiling point constituents. of crue petroleum, which consists in steam distilling and fractionating said residue without substantial cracking, diluting a fraction or fractions with a lower boillng point petroleum prod: uct, chilling the fractions so that the wax shall be precipitated and the oil maintained in fluid condition, centrifuging the chilled products with a heavier carrier liquid and separately discharging from the centrifuge the separated wax and the wax freed oil.

4. lhe method of'treating a residue contain'ing' wax in the intermediate form, which consists in steam distilling off a portion of such residue without changing the character of the wax substantially, diluting the'distillate with a lower boiling point petroleum distillate beyond the point of saturating the wax, chilling the diluted product so as to precipitate the wax, centrifuging the chillled product with water as a carrier liquid, separately discharging the wax and the wax freed oil, and distilling the wax freed oil to separate the diluent therefrom.

5. The method of obtaining lubricating oils from petroleum which comprises distilling the petroleum with fractionation thereof and the separation of a fraction containing lubricating stock together with wax in the intermediate form, diluting such fraction' with naphtha, so as to render the oil sufficiently lighter than the wax to permit their separation by centrifugal force, chilling the diluted product so as to precipitate the wax while retaining the oil 1n its fluid condition, and centrifuging the chilled product so as to effect the continuous separation and separate discharge of the oil and the wax separated therefrom.

6. The method of obtaining lubricating oils from petroleum which consists in dis-' tilling the petroleum with isolation of a distilled lubricating stock, distilling the lubrieating stock with the production of a residue comprising the bulk thereof,-the distillations being effected without substantially cracking the oil, diluting the residue with naphtha so as to render the oil sufiiciently centrifugal separation thereof, chilling the diluted product gradually with recipitation of the wax while maintaining tl fe fluidity of the oil, and centrifuging the chilled prodnot so as to effect the separation of the wax separating the distillate into fractions con-.

taining wax in the crystalline and in-the intermediate forms respectively, diluting the fraction containing the intermediate wax with naphtha so that the oil shall have a lower specific gravity than the wax, chilling the diluted product without substantial agitation, so as to precipitate the wax while retaining the fluid condition of the oil, and centrifuging the chilled product so that the oil and wax are separated and separately discharged.

8. The process oftreating a petroleum product containing wax in the intermediate form which consists in diluting said product with naphtha of not heavier than 65 Be, chilling the diluted product, and centrifu 'ng the chilled product to dischar e t e wax and the oil separately.

9. he \process of treating a petroleum product containing wax in the intermediate form wlrich consists in diluting said product with naphtha, chilling the diluted product to -a temperature below zero F. we maintaining the fluidity of the 011, and centrifu 'ng the chilled product to dis- 'charge t e wax and the oil separately.

Signed at Philadelphia, in the county pf Philadelphia and State of Pennsylvania,

this third day of April, 1922.

PHILIP 'll. SHARPLES.

50 lighter than the wax to permit continuous 

